Bubblewrap is an unprivileged sandboxing tool namespaces-powered chroot-like solution.
Bubblewrap misuses temporary directories in /tmp as a mount point.
This flaw may allow possible execution of code or prevention of running Bubblewrap.
There is no known workaround at this time.
All Bubblewrap users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=sys-apps/bubblewrap-0.4.1"